1. Field of the Invention
This invention relates to a light-sensitive composition containing an unsaturated monomer and a photopolymerization initiator, and optionally further containing a linear organic high molecular polymer, and especially to a light-sensitive composition which is capable of providing photohardened images and useful for preparation of presensitized plates from which lithographic printing plates are to be prepared, photoresist or the like. More specifically, the present invention relates to a new light-sensitive composition wherein a phenomenon is inhibited that the photopolymerization initiator moves on the surface of the light-sensitive layer and deposits or in some case aggregates and crystallizes.
2. Description of the Prior Art
Methods for reproducing an image according to photographic processes using, as a light-sensitive composition, a composition comprising a polymerizable ethylenically unsaturated compound and a photopolymerization initiator and if necessary a linear organic high molecular polymer, a thermal polymerization inhibitor, etc. have hitherto been widely known. That is, the light-sensitive composition is photopolymerized by irradiation of actinic light and insolubilized, as disclosed in Japanese Patent Publication for Opposition Purpose (hereinafter referred to as "J.P. KOKOKU") Nos. 35-5093 and 35-8495 and the like. Therefore, a desired photopolymerization image can be formed by making the light-sensitive composition a proper film, irradiating the film with actinic light through a negative transparency of a desired image and removing only unexposed areas with a proper solvent (hereinafter merely referred to as development). It goes without saying that this type of light-sensitive compositions are very useful as light-sensitive materials for presensitized plates, photoresists or the like.
As photopolymerization initiators there are mentioned, for example, vinylhalomethyl-s-triazine compounds disclosed in U.S. Pat. Nos. 3,987,037 and 3,954,475. Compounds described therein as those especially valuable include the following compounds. ##STR3##
These compounds have a disadvantage of causing during storage a phenomenon that they move onto the surface of the light-sensitive layer and deposit, and in some case aggregate and crystallize (the so-called crystallization phenomenon). Therefore, a light-sensitive composition wherein a above-mentioned photopolymerization initiator is used is poor in stability over time.